Blood levels of the nerve damage marker neurofilament light provide a reliable picture of multiple sclerosis activity in both the relapsing-remitting and progressive forms of the disease, a Swedish study reports.
The University of Gothenburg researchers also discovered a close link between its levels in blood and spinal fluid. This means the marker can be analyzed without a spinal tap.
Another finding was that the factor can distinguish between people with inflammatory neurological diseases such as MS, people with non-inflammatory brain conditions, and healthy people.
Researchers published their study, “Monitoring disease activity in multiple sclerosis using serum neurofilament light protein,” in the journal Neurology.
The marker is a protein found in nerve cells. When the cells become damaged, the protein leaks into the spinal fluid and blood. Researchers are increasingly realizing its value in studying MS activity.
Three hundred seventy-three people took part in the Swedish study — 286 MS patients, 45 people with other neurologic conditions, and 42 healthy controls. The MS group included people in all the disease categories — relapsing-remitting MS, or RRMS; primary progressive MS, or PPMS; and secondary progressive MS, or SPMS.
The MS group had higher levels of the marker than the other two groups in both their blood and spinal fluid, researchers discovered. And the concentrations in blood mirrored those in spinal fluid.
In both RRMS and progressive MS patients, higher levels of the marker indicated more disease activity — in the form of relapses and numbers of inflammatory brain lesions. People with more inflammatory lesions also had higher levels of the marker than those with fewer lesions. Lesions are areas where diminished levels of protective myelin protein cause nerve cell damage.
Researchers also discovered that MS therapies lowered levels of the marker. The concentrations dropped further if the subgroup of patients in this part of the study increased their treatment or switched from standard drugs such as interferon-beta to more effective ones like Lemtrada (alemtuzumab).
In contrast, untreated patients continued to have higher levels of the marker.
Researchers found a weak correlation between levels of the marker and patients’ disability, but no correction between levels of the marker and how long a person had had MS. The team used the Expanded Disability Status Scale to measure disability.
Another finding was that age and sex did also not affect the marker’s levels.
Researchers around the world are looking at whether the protein can help identify various features of MS development.
A recent study suggested the marker may replace magnetic resonance imaging scans as measures of patients’ disease activity.
The attention that researchers are paying to it also suggests it may become a mainstay of doctors’ monitoring of MS activity in years to come.